Fluid circulation type electric base-board space heater



1956 B. REYNOLDS EIAL 2,772,342

FLUID CIRCULATION TYPE ELECTRIC BASE-BOARD SPACE HEATER Filed July 8, 1954 ll ii A lfljNkENToljz$ gya 4 /20 BY bm' yi h e/a/r MC,

ATTORNEY United States Patent FLUID CIRCULATION TYPE ELECTRIC BASE-BOARD SPACE HEATER Loyal B. Reynolds and Harry G. Welch, Seattle, Wash.

Application July 8, 1954, Serial No. 442,132

2 Claims. (Cl. 219-38) This invention relates to a fluid circulation type electric base-board space heater.

An object of this invention is to provide a fluid circulation type electric base-board heater in which heat radiating means and electric heat generating means with controls responsive to fluid temperature are embodied in a single unit heater suitable for individual room heating or for substantially any space heating where electric current is used.

Another object is to provide a fluid circulation type sealed base-board heater having an electric heating element therein and provided with an expansion chamber which is calibrated or sized so that it will safeguard the heater by taking care of normal expansion of the fluid in the heater and at the same time will eliminate noise by bringing about an increase in pressure suflicient to prevent boiling of the fluid which is in close proximity to the electric heating element.

Another object is to provide a fluid circulation type electric base-board heater which can be initially filled with fluid and then sealed and which, thereafter, will operate as a sealed unit without requiring the addition of fluid, thus minimizing servicing requirements and insuring eflicient and uniform operation and reducing the danger of injury to the heater such as might occur if the heater were operated with an insufficient supply of fluid therein.

Other objects are to provide a fluid circulation type electric base-board heater which is simple in construction, not expensive to manufacture and which is highly eflicient in operation and economical in its consumption of electric current in proportion to the amount of useful heat delivered.

Another object is to provide a fluid circulation type electric base board heater embodying two substantially parallel horizontal heat radiating pipes disposed one above another and communicatively connected at their ends forming a fluid circulation loop, the lower pipe having a heating element chamber adjacent one end and having an electric heating element extending longitudinally into said chamber and said lower pipe being offset downwardly adjacent the inner end of the chamber, thereby tending to cause fluid which is heated in said chamber to rise to said upper pipe and flow outwardly through said upper pipe and return to said chamber by way of said lower pipe.

Other objects of the invention will be apparent from the following description taken in connection with the accompanying drawings.

Figure 1 is a view in elevation, with parts broken away, showing a fluid circulation type electric base-board heater constructed in accordance with this invention.

Fig. 2 is a view in longitudinal section on a larger scale than Fig. 1 showing this heater, the heat radiating pipes being broken away and the base board being omitted.

Fig. 3 is a cross sectional view of the base-board and heater, taken substantially on broken line 33 of Fig. 1.

2,772,342 Patented Nov. 27, 1956 Like reference numerals designate like parts throughout the several views.

The drawings show a Wall 5, a floor 6 and a metal base-board of conventional construction comprising a back member 7 and a front member 8. The back member 7 is secured to the wall 5 and has outwardly extending brackets 9 from which the front member 8 is supported. At least one opening 10 is provided at the bottom of the front member 8 for the entrance of cold air and at least one opening 11 is provided near the top of the base-board for the outlet of warm air. The previously described parts constitute a conventional metal base-board in which this heater is installed.

This heater comprises a fluid heating portion, shown at the left in Fig. l and shown on a larger scale in Fig. 2, and a heat radiating portion, shown at the right in Fig. 1. Both the fluid heating portion and the heat radiating portion are entirely housed within the base-board. The heat radiating portion, as shown in Fig. 1, comprises an upper run of substantially straight pipe 12 and a lower run of substantially straight pipe 13 communicatively connected with each other by a one hundred and eighty degree bend portion 14. The two pipes 12 and 13 are parallel and are supported horizontally within the base-board by the brackets 9 and the pipe 12 is spaced above the pipe 13. Heat radiating fins 15 are provided on at least the upper run of pipe 12. This makes the pipe 12 the chief source of heat radiation.

A fluid heater is connected with the ends of the pipes 12 and 13 remote from the bend 14, this being hereinafter referred to as the inner end of pipes 12 and 13. This fluid heater comprises a lower pipe 16 having one end connected by a reducer coupling 17 with the lower radiator pipe 13. The pipe 16 is of larger diameter than the pipe 13. The other end of the pipe 16 is connected by a T 18 and nipple 19 with the smaller end of a fitting 20. The larger end of the fitting 20 is internally threaded to receive the externally threaded hub 21 of a resistance type electric heater. Sheathed heating elements 22 are carried by the hub 21 and extend longitudinally within a fluid heating chamber 35 formed by the nipple 19, T 18 and pipe 16. Electrical conductors 23 supply current to the heating elements 22. A heat responsive member 24 extends through the hub 21 and into the liquid heating chamber 35 and a switch housing 25 is connected with the outer end of said stem 24. Members 24 and 25 are parts of a conventional aquastat which controls the supply of electric current to the heating elements 22 and is responsive to the temperature in the fluid heating chamber 35.

The fluid heating chamber 35 formed by parts 16, it; and 19 is of larger diameter than the pipe 13. This difference in diameter will offset the top portion of the pipe 13 below the top portion of the liquid heating chamber enough for practical purposes if the reducer 17 is symmetrical or concentric. However we have shown the reducer 17 to be eccentric and positioned so that it will offset the pipe 13 downwardly. This prevents fluid circulation in the wrong direction, as hereinafter explained.

The side outlet of the T 18 is positioned uppermost and is connected by an elbow 26 with a nipple 27. The nipple 27 is connected by a T 2d and another nipple 29 and another T 30 with the upper heat radiating pipe 12. A pressure operated relief or safety valve 31 is connected with the T 28. An expansion chamber 32 is positioned above and connected wtih the T 38 The expansion chamber 32 is calibrated or sized so that it will safeguard the heater by taking care of normal expansion of the fluid, usually water, therein, and at the same time will provide for enough increase in pressure as the temperature rises to prevent the liquid immediately around the element 22 from boiling and making noise. It has been found that this expansion chamber should be a of such a size or volume that, when the temperature of a sealed heater which contains water is raised to about two hundred degrees Fahrenheit the pressure in said heater will not be less than fifteen pounds per square inch and preferably will be approximately twenty-eight pounds per square inch. When the heater .is in use the temperature of the fluid, such as water, ascending from the heating chamber 35 to the upper heat radiating pipe 12 will ordinarily not exceed two hundred degrees Fahrenheit. However, at pressures below fifteen pounds per square inch, boiling of the water in actual contact with the heating element 22 may occur when the temperature of the water leaving the chamber 35 is considerably below two hundred degrees.

Preferably the supply of electric current to the heater 22 is controlled jointly by the aquastat 24, 25 and by a room thermostat, the arrangement being such that when either the switch in the aquastat housing 25 or the switch of the room thermostat is open the circuit to the heating elements 22 will be broken. Both of these switches are closed by a drop in temperature and opened by a rise in temperature.

The pipe 13 and heating chamber 35 constitute a lower, straight, horizontal fluid conduit. The pipe 12 and parts 30, 29, 28 and 27 constitute an upper, straight, horizontal fluid conduit. These two conduits are parallel and spaced one above another. They are communicatively connected at their outer ends by the bend 14 and at their inner ends by the elbow 26. When the heating elements 22 are energized the fluid will circulate in the direction shown by the arrows in Fig. 2 and most of the heat will be radiated by the fins 15 on the upper pipe 12. Satisfactory operation is obtained if the temperature drop between the water leaving the heating chamber 35 and the water returning to said chamber is about twenty degrees. The expansion chamber 32 compensates for expansion of the fluid in the heater produced by temperature increase and also insures enough pressure increase in the heater to prevent boiling of the fluid around the heater and to thus eliminate noise due to boiling. The safety valve 31 is only an emergency device and will not operate when the heater is functioning normally. Thus there is not any way for the fluid to escape from the heating system and the heater does not need to have any fluid added.

The previously explained fluid conduits constitute a loop formed of two parallel runs of vertically spaced apart horizontal pipe communicatively connected at their ends and with the heater 22 extending into the heating chamber end portion of the lower run of pipe. The outlet from this heating chamber 35 is from the uppermost part of said chamber through the T 18 and this outlet is above the uppermost part of the passageway in the pipe 13 forming a slight drop between the uppermost part of the chamber 35 and the uppermost part of the pipe 13. This drop prevents heated fluid from leaving the chamber 35 by way of the pipe 13 and insures a gravity fluid circulation in the direction indicated by the arrows in Fig. 2.

The foregoing description and accompanying drawings clearly disclose a preferred embodiment of this invention but it will be understood that this disclosure is merely illustrative and that changes may be made within the scope and spirit of the following claims.

We claim:

1. A fluid type base-board space heater comprising a horizontal upper run of pipe; a horizontal lower run of pipe positioned parallel with and in spaced relation below said upper run of pipe, said lower run of pipe having at one end a fluid heating chamber provided with a top wall which is vertically offset above the top wall of the remainder of said lower run of pipe; an electric heating element extending into said fluid heating chamber; a fluid conduit communicatively connecting the uppermost portion of said fluid heating chamber with the adjacent end of said upper run of pipe; another fluid conduit communicatively connecting the end portions of said two runs of pipe remote from said heating chamber, said two runs of. pipe and end connecting fluid conduits forming a closed fluid circulation loop which is sealed against the escape of fluid, the upward vertical offset of the upper wall of the fluid heating chamber relative to the upper wall of the remainder of the lower run of pipe predetermining the direction of circulation of fluid in the loop and causing heated fluid from the chamber to flow first through said upper run of pipe and then through said lower run of pipe back to the chamber; and expansion chamber means extending above and communicating with the uppermost portion of said upper run of pipe, said expansion chamber insuring silent operation and maintaining low pressure in said closed and sealed fluid circulation loop.

2. A fluid type base-board space heater comprising a substantially straight lower horizontally positioned fluid conduit forming a fluid heating chamber; an electric heating element projecting into and extending longitudinally within said heating chamber; an upper fluid conduit disposed parallel with said heating chamber and spaced above the same; a transverse fluid conduit communicatively connecting said upper fluid conduit with the uppermost part of said heating chamber adjacent the location where said heating element enters said fluid heating chamber; a U shaped heat radiating pipe of smaller cross sectional area than said fluid heating chamber, said heat radiating pipe comprising two spaced apart parallel branches communicatively connected with each other at their outer ends and having their inner ends communicatively connected respectively with the ends of said upper fluid conduit and said fluid heating chamber, the upper branch of said heat radiating pipe being axially aligned with said upper fluid conduit and the lower branch of said heat radiating pipe being connected with the end of said fluid heating chamber with the uppermost Wall of said lower heat radiating pipe branch vertically offset downwardly below the uppermost wall of said heating chamber and the lowermost wall of said lowermost heat radiating pipe branch substantially flush with the lowermost wall of the heating chamber, said vertical oflset promoting a gravity circulation of fluid directionally from said lower heat radiating pipe branch toward said heating chamber; heat radiating fins on said upper heat radiating pipe branch; and means forming a sealed expansion cham ber communicating with and extending above said upper fluid conduit and upper heat radiating pipe branch.

References Cited in the file of this patent UNITED STATES PATENTS 1,788,515 Gannon Ian. 13, 1931 2,000,438 Dougherty May 7, 1935 2,063,152 Davidson Dec. 8, 1936 2,432,917 Maurer Dec. 16, 1947 2,471,674 Cote May 31, 1949 2,477,778 Wright Aug. 2, 1949 2,509,138 Dorn May 23, 1950 

